Six Sigma Certification: Belt Levels, ASQ vs. IASSC, Costs and How to Choose

What Six Sigma certification is

Six Sigma is a data-driven approach to reducing defects and variation in processes. A Six Sigma certification shows that you understand its methods, most often the DMAIC cycle (Define, Measure, Analyze, Improve, Control), and in many cases that you have applied them. If you are new to the method, start with what is Six Sigma and the guide to the DMAIC methodology.

There is no single, legally recognized Six Sigma certification. Different organizations award different credentials, and employers decide how much each is worth. That is why the first question to ask about any program is: who issues the credential, and what did I have to do to earn it?

The belt levels

Six Sigma borrows martial-arts belt names to describe levels of expertise. The names are widely used, but exact definitions vary by organization.

For more detail on how the levels relate, see our guide to Six Sigma belt rankings. If your employer also uses lean methods, read Six Sigma vs. Lean Six Sigma.

Three kinds of certificate: know the difference

Many people combine them: take a course for the learning, then sit an independent exam for the credential. Whichever you choose, a completed project with documented results is often more persuasive in an interview than a certificate on its own.

ASQ requirements and fees

The American Society for Quality (ASQ) is one of the best-known certifiers. Its published requirements and fees at the time of writing are summarized below. Check ASQ’s certification pages for current details before you apply.

ASQ members save $100 on the initial exam fee. The exams are open book, and candidates bring their own bound reference materials. The computer-based exams are offered in English only. Recertification rules are published separately by ASQ.

Note the difference in requirements: the Yellow Belt is open to anyone, but the Green and Black Belt exams require documented work experience, and the Black Belt requires completed projects. That makes them harder to obtain than many course-based certificates, and often more credible for the same reason.

IASSC at a glance

The International Association for Six Sigma Certification (IASSC) is another independent certifier. Its certification page lists Yellow, Green and Black Belt exams with 60, 100 and 150 proctored questions respectively, and says exams can be taken through an on-demand web-based system or at testing centers. The page lists no prerequisites or project requirements for any level, and no prices; vouchers are bought through IASSC’s site.

Because the two bodies differ on prerequisites, the practical difference is often this: ASQ’s Green and Black Belts verify experience and, for the Black Belt, project work; IASSC’s exams test knowledge. Employers in some industries, and in some countries, prefer one or the other, so look at job postings for roles you want.

Which belt should you start with?

Many people begin with the Green Belt. It is a common starting point for working professionals, and its tools (process mapping, data collection, root cause analysis, control charts) are useful even if you never become a Black Belt. If your employer practices both methods, a Lean Six Sigma certificate may fit better; see our overview of Lean Six Sigma certificate programs.

How to prepare

1. Download the official Body of Knowledge from the certifier. Every exam question is drawn from it.
2. Learn the DMAIC cycle thoroughly, including the tools used in each phase. Our guides to DMAIC and DMADV explain the difference between improving an existing process and designing a new one.
3. Practice on real data. Apply a tool to a process you know, such as lead times, error rates or call-handling time.
4. Build a reference binder. For open-book exams, a well-organized, tabbed binder of formulas and definitions saves time. Check that your materials meet the certifier’s rules, such as being bound.
5. Take timed practice exams and review every mistake. The ASQ exams run more than four hours at Green and Black Belt level, so stamina matters.
6. Document a project. Record the problem, baseline data, actions and measured results. This also supports a Black Belt application.

Training options

You can study alone with the Body of Knowledge and a good textbook, or take a structured course. Online marketplaces carry many Six Sigma courses from independent publishers and universities. Content, depth and recognition vary a lot, so check the syllabus, who teaches it, whether a project is included, and whether the course prepares you for a specific exam.

• Browse Six Sigma courses and certificates on Coursera
• Browse Six Sigma Green Belt and Yellow Belt courses on Udemy

For an academic route, compare our pages on Six Sigma Green Belt courses, Lean Six Sigma Black Belt courses and Lean Six Sigma certificates. A Lean Six Sigma certification requirements infographic gives a quick visual summary, and all of our process-improvement guides are collected in the Six Sigma hub.

Disclosure: some links on this page are affiliate links. If you buy through them, we may earn a commission at no extra cost to you. VillanovaU is an independent guide and is not affiliated with ASQ, IASSC, any university or the platforms listed. Our guidance follows the certifiers’ own published requirements, not commission rates.

Frequently asked questions

What is Six Sigma certification?

It is a credential showing that you understand Six Sigma methods for reducing defects and variation, and in many cases that you can apply them. It is awarded at levels called belts, and different organizations issue their own versions.

How much does Six Sigma certification cost?

It depends on the issuer. ASQ’s current exam fees are $434 for the Yellow Belt, $483 for the Green Belt and $585 for the Black Belt, with $100 off for ASQ members. Training courses are a separate cost and vary widely.

Which Six Sigma belt is best to start with?

Most people start with the Green Belt, which is the level most commonly requested by employers. If you are completely new, the Yellow Belt gives a foundation without an experience requirement.

Do you need experience to get certified?

For ASQ, the Yellow Belt has no experience requirement, the Green Belt requires three years of relevant on-the-job experience, and the Black Belt requires three years plus completed projects with signed affidavits. IASSC’s page lists no prerequisites.

What is the difference between ASQ and IASSC?

Both are independent certifiers. ASQ’s Green and Black Belts require documented experience, and the Black Belt requires projects. IASSC’s page lists no prerequisites and tests knowledge through proctored exams of 60 (Yellow), 100 (Green) and 150 (Black Belt) questions.

Are the Six Sigma exams open book?

ASQ’s exams are open book: candidates bring their own bound reference materials. Rules for other certifiers differ, so check the one you plan to use.

Is Six Sigma certification worth it?

It can be, if your industry values process improvement and your employer or target employers recognize the credential. It is most persuasive when paired with a project that delivered measured results.